The story of Rachav (Rahab) and the scarlet cord in the biblical account of Jericho (Joshua 2, 6) carries significant symbolism and connects to certain Temple practices mentioned in the Torah.

In Joshua 2, the spies sent by Joshua to scout Jericho are hidden by Rachav (Rahab) the prostitute. She asks that her family be spared when the Israelites attack, and the spies instruct her to hang a scarlet cord from her window as a sign. This scarlet cord becomes the mark that saves (Rachav’s (Rahab’s) household from destruction when Jericho falls (Joshua 6).

The scarlet cord is reminiscent of the scarlet cord of wool tied around the horns of the scapegoat (the goat “for Azazel”) (m. Yoma 4:2) in the Yom Kippur rituals prescribed in Leviticus 16. This goat carried the sins of Israel into the wilderness in a symbolic removal of iniquity.

Some see Rachav (Rahab), a Gentile, as representing those outside the covenant community who place faith in the God of Israel. Her scarlet cord marks her home for redemption, just as the scarlet cord marked the scapegoat bearing away sins. Her family is brought into the Israelite people through this act.

So the scarlet cord connects Rachav’s (Rahab’s) redemptive act – protecting the spies and siding with the Israelites against her own people – to the theological concepts of sin-bearing and atonement represented by the Temple’s Yom Kippur ritual. The fact that she covenants to protect the spies results in a new covenantal status for her family within Israel.

In essence, a sovereignly given mark (the scarlet cord) falls on an unlikely recipient Rachav (Rahab) to seal a covenant through which redemption comes to her household, prefiguring Israel’s role to the nations.

Ref. Scapegoat: The Origins of the Crimson Thread – TheTorah.com